e-field in cst

hello All,

My problem regards E-field probe signal results under different mesh settings.

I have an antenna model with an E-field probe set in its far-field region.
In my opinion the antenna is well meshed, i.e. the mesh "sees" all the important parts.
As I thicken the mesh density the E-field results change.

Has anyone encountered this kind of problem?
Any comments regarding this issue are more than welcome...

Thanks,
P.

Hi Pushhead,

can you explain in what way they are different ? I mean expanded in time, different amplitude, ... ?

Also, note that when you try to increase the mesh density the time step is reduced leading to higher sampling rate in the E-field. So, some details which may have not been obvious using the coarse mesh became more obvious. You shouldn't only talk about spatial accuracy

best regards,
Adel

Hello Adel_48,

The difference is mainly in the shape and amplitude - please find attached an example snapshot of the time signals. This is the same probe and model under different mesh settings.
I Agree, the picture "looks" like a sampling rate problem.
However, the bigger issue here is what should one do to rely on an E-probe result?

All comments and responses are welcome.

BR,
P.

Hi Pushhead,

this shape looks very strange, are you sure there was no mistake near about 11ns. Since the pulse shape looks "flat" in this region which looks non-physical. may be it is a problem or glitch some where ?

Also, did you enable "equilibrate mesh" option in the mesh dialog box? since using dense mesh usually leads to an increase in the numerical dispersion.

Hope this will help,
Adel

Hi Adel,

there is actually nothing (vacuum) in the 11ns area, just the E-probe hanging in the antenna far-field zone. Haven't tried "Equilibrate mesh"-but will try soon.

Thanks,
BR,
P.

Hi

hard to tell without seeing the model. You you post it here? Please keep in mind that the "farfield probe" uses a near-field to far field transformation. Have you checked the full radiation pattern of both examples at some frequencies?. Are they identical (as they should)?

F